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The interest stems from that accurate measurements of the unit cell volume, atomic weight and mass density of a pure crystalline solid provide a direct determination of the Avogadro constant. [3] The CODATA recommended value for the molar volume of silicon is 1.205 883 199 (60) × 10 −5 m 3 ⋅mol −1, with a relative standard uncertainty of ...
Column number density is a kind of areal density, the number or count of a substance per unit area, obtained integrating volumetric number density along a vertical path: ′ =. It's related to column mass density , with the volumetric number density replaced by the volume mass density.
The molar mass of atoms of an element is given by the relative atomic mass of the element multiplied by the molar mass constant, M u ≈ 1.000 000 × 10 −3 kg/mol ≈ 1 g/mol. For normal samples from Earth with typical isotope composition, the atomic weight can be approximated by the standard atomic weight [ 2 ] or the conventional atomic weight.
It is a mass-specific intrinsic property of the substance. It is the reciprocal of density ρ and it is also related to the molar volume and molar mass: = = ~ The standard unit of specific volume is cubic meters per kilogram (m 3 /kg), but other units include ft 3 /lb, ft 3 /slug, or mL/g. [1]
The molecular mass and relative molecular mass are distinct from but related to the molar mass. The molar mass is defined as the mass of a given substance divided by the amount of the substance , and is expressed in grams per mol (g/mol).
The SI value of the mole was chosen on the basis of the historical definition of the mole as the amount of substance that corresponds to the number of atoms in 12 grams of 12 C, [1] which made the mass of a mole of a compound expressed in grams, numerically equal to the average molecular mass or formula mass of the compound expressed in daltons.
The conversions to and from the molar concentration, c 1, for one-solute solutions are = +, =, where ρ is the mass density of the solution, b 1 is the molality, and M 1 is the molar mass (in kg/mol) of the solute.
When expressed in percent, it is known as the mole percent or molar percentage (unit symbol %, sometimes "mol%", equivalent to cmol/mol for 10 −2). The mole fraction is called amount fraction by the International Union of Pure and Applied Chemistry (IUPAC) [ 1 ] and amount-of-substance fraction by the U.S. National Institute of Standards and ...